Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities
Net income (loss)	$ 1,481.6	$ 1,023.6
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Amortization of deferred acquisition costs	173.8	264.0
Additions to deferred acquisition costs	(307.2)	(293.6)
Accrued investment income	(54.0)	(67.8)
Net cash flows for trading securities	55.3	25.6
Premiums due and other receivables	(158.2)	68.9
Contractholder and policyholder liabilities and dividends	2,693.5	1,594.4
Current and deferred income taxes (benefits)	456.0	75.6
Net realized capital (gains) losses	(564.1)	(214.5)
Depreciation and amortization expense	144.8	139.6
Real estate acquired through operating activities	(55.2)	(31.2)
Real estate sold through operating activities	1.3	21.4
Stock-based compensation	62.2	58.7
Other	(301.1)	262.6
Net adjustments	2,147.1	1,903.7
Net cash provided by (used in) operating activities	3,628.7	2,927.3
Investing activities
Available-for-sale securities: Purchases	(10,425.7)	(10,590.0)
Available-for-sale securities: Sales	1,011.2	1,138.1
Available-for-sale securities: Maturities	6,577.2	5,836.0
Mortgage loans acquired or originated	(2,036.5)	(2,116.3)
Mortgage loans sold or repaid	1,297.4	1,440.8
Real estate acquired	(113.6)	(90.2)
Real estate sold	457.1	35.5
Net (purchases) sales of property and equipment	(133.3)	(109.1)
Net change in other investments	48.5	(42.4)
Net cash provided by (used in) investing activities	(3,317.7)	(4,497.6)
Financing activities
Issuance of common stock	143.1	25.7
Acquisition of treasury stock	(218.1)	(245.2)
Proceeds from financing element derivatives	0.1	0.3
Payments for financing element derivatives	(59.5)	(67.3)
Excess tax benefits from share-based payment arrangements		5.9
Purchase of subsidiary shares from noncontrolling interest	(13.3)	(2.4)
Dividends to common stockholders	(398.5)	(341.1)
Issuance of long-term debt		11.0
Principal repayments of long-term debt	(56.2)
Net proceeds from (repayments of) short-term borrowings	4.9	(143.4)
Investment contract deposits	8,244.4	8,108.5
Investment contract withdrawals	(7,963.1)	(6,201.4)
Net increase (decrease) in banking operation deposits	79.8	69.6
Other	0.8	3.5
Net cash provided by (used in) financing activities	(235.6)	1,223.7
Net increase (decrease) in cash and cash equivalents	75.4	(346.6)
Cash and cash equivalents at beginning of period	2,719.6	2,564.8
Cash and cash equivalents at end of period	2,795.0	$ 2,218.2
Asset and liability changes resulting from exchange agreement to exit real estate joint ventures:
Real estate properties received	743.2
Long-term debt assumed on real estate properties received	269.0
Increase in other investments due to discontinuing equity method accounting	$ 222.4